The death toll brought on by floods, landslides and bridge collapses in India's monsoon-hit state of Kerala has risen to 77 as heavy rainfall threatened new areas.

Authorities in the southern state, which is home to 33 million people, have placed local agencies on the highest alert level in what has turned out to be Kerala's worst monsoon in almost a century.

"All districts are under red alert as more rains are expected in the next 24 hours," an official from the Kerala State Disaster Management Authority told AFP on Thursday.

Kerala is battered by the monsoon every year but the rains have been particularly severe since August 8, flooding hundreds of villages and prompting the authorities to suspend flights in and out of the region.

More than 60,000 people have sought shelter in relief camps and the army and navy have been called in to assist with rescue operations, airlifting people to hospital, according to the official.

Unconfirmed local media reports mentioned a much higher toll and cited ongoing efforts to reach many flooded areas.

Prime Minister Narendra Modi said on Thursday that he was "praying for the safety and well-being of the people of Kerala" and has ordered the Defence Ministry to "further step up the rescue and relief operations across the state."

Kerala Chief Minister Pinarayi Vijayan's office announced on Twitter that Kochi International Airport - the main gateway to the region - would be closed until Saturday "due to heavy rains and resultant flooding".

Vijayan held emergency meetings with rescue officials in the state late on Wednesday and discussed the situation with Prime Minister Narendra Modi.

The chief minister has requested the deployment of additional personnel from the Indian army, navy and other emergency forces who are already working across the state, famed for its pristine palm-lined beaches and tea plantations.

"Our state is in the midst of an unprecedented flood havoc," Vijayan said earlier this week. "The calamity has caused immeasurable misery and devastation."

Authorities have opened the gates of 34 reservoirs as water reached dangerous levels.

Vijayan's office on Wednesday said that the authorities were also worried about rising water levels in the massive Mullaperiyar dam, and urged officials in the neighbouring state of Tamil Nadu to release water from the reservoir.

Hundreds of villages have been flooded, more than 10,000 kilometres of roads and thousands of homes have been destroyed or damaged across the state, officials said.

"We have asked all airlines, domestic and foreign, to reschedule their Cochin flights either from Trivandrum or from Calicut," Suresh Prabhu, India's civil aviation minister said on Twitter.

"For international flights, this will require special dispensation which has been granted considering the emergency DGCA (Directorate General of Civil Aviation) is coordinating," he added.

More than one million foreign tourists visited Kerala last year, according to official data. (Aljazeera)

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